Power systems utilize a variety of electrical devices and connectors to deliver electricity from a power station or generator to customers. Some power systems utilize a three-tiered approach that utilizes high-voltage power lines with voltages in the range from approximately 60 kV to 100 kV, medium-voltage power lines with voltages in the range from approximately 4 kV to 60 kV, and low-voltage power lines with voltages in the range from approximately 90V to 600V.
In these three-tiered power systems, high-voltage power lines typically connect a power station or generator to a substation. The substation serves a particular area such as a neighborhood and includes a transformer to step-down the voltage from high voltage to medium voltage. Typically, multiple sets of medium-voltage power lines connect the substation to local distribution transformers. The distribution transformers typically serve the customers in close proximity to the distribution transformer and step-down the voltage from medium voltage to low voltage for use by the customers.
The power lines used to deliver electricity to customers have also been used to transmit and receive communications signals. For example, power lines have been used by utility companies to transmit and receive communications signals to monitor equipment and to read meters. Power lines have also been used to provide broadband communications for customers. Various techniques have been developed to couple broadband communications signals to medium-voltage power lines. These broadband communications signals typically occupy frequencies in the 2-50 MHz region. One approach to coupling communications signals to these medium-voltage power lines is to use the intrinsic capacitance of metal oxide varistor (MOV) lightning arresters to couple a portion of the communications radio frequency signals onto medium-voltage power lines. Most MOV lightning arresters have a special device attached to the bottom of the arrester assembly to explosively disconnect the grounding wire in case of a current fault. This device usually consists of a grading resistor in parallel with an air-gap and small gunpowder charge.